Ion release from bioactive dental liner materials by ion chromatography

Bioactive liner materials are used to promote dentine bridge formation, reduce early pulp inflammation, and support remineralization. Ion release is a key factor in understanding their role in biomineralization processes. This study is the first to employ a single method to quantitatively and qualitatively analyze the simultaneous release of multiple ions from various liner materials.

Ion chromatography was used to measure the release of 16 anions and cations into water, along with pH changes, on days 1, 4, 7, 14, and 30. The tested liner materials included an experimental liner/base from Solventum (EXP), TheraCal LC (TC), Dycal (DY), Lime-Lite Enhanced (LL), Fuji Lining LC Paste Pak (FL), and Medcem MTA (MC). Statistical analysis included the Shapiro-Wilk, Kruskal-Wallis, and Friedman-tests (α = 0.05).

DY exhibited the highest pH (∼12) after 30 days, followed by MC (∼10), both significantly higher than FL. Of 16 tested ions, 9 were cumulatively released in quantifiable amounts. FL showed the highest F⁻ (279 µg/mL) and Sr²⁺ (128 µg/mL) release. LL released the most Cl⁻ (101 µg/mL) and PO₄³ ⁻ (31 µg/mL), while SO₄²⁻ peaked in TC (111 µg/mL). DY released the most Ca²⁺ (950 µg/mL). EXP showed the highest NH₄⁺ levels, MC the highest K⁺, and LL the highest Na⁺.

The differences in ion release and pH values represent a mosaic stone in understanding the biomineralization effects of liner materials, particularly when considered alongside monomer release data in future studies addressing biological and clinical contexts.